△ABC,a>b,sin(A+pi/4)=4/5,cos(pi/4+B)=5/13,q:sinC

问题描述:

△ABC,a>b,sin(A+pi/4)=4/5,cos(pi/4+B)=5/13,q:sinC

sin(A+π/4)=4/5
cos(A+π/4)=±3/5
cos(A+π/4)=3/5>5/13=cos(π/4+B)
∴A+π/4